A blue oak woodland near Allum Rock, above San Jose (B24).

Springtime at Pacheo Pass State Park (PP2).

Wind-flagged blue oaks at Pacheo Pass (PP2).

Tree-ring collections from Pacheo Pass (PP2) and Rock Springs Ranch (B27).

Professor David Stahle extracts a specimen from a dead blue oak at Rock Springs Ranch (B27).

Professor David Meko samples a living blue oak tree near Folsom Lake (AR2).

Blue oak woodland (pale green) and live oak woodland (dark green in draw) at the University of California Hastings Natural History Reserve in the upper Carmel Valley (HAS).

A mature blue oak and European grasses at the Machesna Mountain Wilderness on the Los Padres National Forest (AC2).

One of the southern most stands of blue oak trees survives on the south slope of Figueroa Mountain above the Santa Ynez Valley (FIG).

Blue oak woodland rapidly transitions to both chaparral and mixed conifer woodlands at Figueroa Mountain (FIG).

Graduate assistant Daniel Griffin measures of the diameter of a 500-year old blue oak tree at Figueroa Mountain on the Los Padres National Forest (FIG).

Snowpack run-off and blue oak woodlands at the Kern River in the southern Sierra Nevada (KR2).

Daniel Griffin samples a young blue oak tree at the San Joaquin Experimental Range in the foothills of the southern Sierra Nevada Mountains (SJR).

Two-hundred to 300-year old blue oak trees in a picturesque savannah setting at the San Joaquin Experimental Range (SJR).

Professor David Stahle extracts a wedge-cut from a standing dead blue oak tree at the SJR.

Research assistant Jesse Edmondson examines a sub-fossil blue oak log at the SJR.

Blue oak woodland (green, right) transitions to a colony of California buckeye (light grey) along the North Fork of the Kaweah River (KAW).

A 350-year old blue oak in Sequoia National Park (KAW).

Research assistant Jesse Edmondson samples a blue oak with a view above the North Fork of the Kaweah River in Sequoia National Park (KAW).

Professor David Stahle examines a CCC-era blue oak stump at the Sequoia National Park (KAW).

Research assistant Daniel Griffin samples a living blue oak near the lower forest border at the Windwolves Preserve (LOB).

Blue oak trees along Los Lobos Creek in the south San Joaquin Valley are highly sensitive to variability in winter and spring precipitation (LOB).

A blue oak woodland below the chaparral-covered slopes of the north Sutter Butte (SUT).

Mature blue oak trees at the northern most site sampled under the CALFED project, along Bear Creek in the Mt. Lassen foothills region (BCC).

A 350-year old blue oak tree displays its heavy and craggy limbs near Bear Creek Canyon (BCC).

Bear Creek Canyon in the northern Sacramento Valley was a salmon run as recently as the late 1990s (BCC).

Blue oak trees and manzanita at Lake Oroville State Recreation Area (FE2).

A gnarly 400-year old blue oak growing on the volcanic bajada a Finley Lake on the Lassen National Forest (FI2).

Unfortunately, this 600-year old blue oak was felled for firewood on the Lassen National Forest, but the stump yielded a fine tree-ring cross-section with well over 500 rings (FI2).

Oak misteltoe (Phoradendron villosum), a parasitic angiosperm in California's oak woodlands.